Apparatus for operating an internal combustion engine with various fuels

An apparatus for operating an internal combustion engine alternatingly with two different types of fuel, comprising:

• two separate fuel circuits each being associated with a respective one of first and second different types of fuel, each of said fuel circuits having at least one electrically triggerable metering device in the form of an injection valve of an internal combustion engine;
• a switch device connected to said injection valves for switching over from one of said fuel circuits to the other of said fuel circuits;
• a single electronic control unit connected to said injection valves and to said switch device for controlling both operation of the engine with the first type of fuel and operation of the engine with the second type of fuel, said electronic control having a power portion with end stages for triggering said injection valves, and each of said end stages being assigned both one injection valve for the first fuel type and one injection valve for the second fuel type;
• and
• said electronic control unit changing a timing of the triggering of said injection valves when changing the operation of the engine from the first fuel type to the second fuel type to compensate for differences in the fuel types.